PSI - Issue 72

Kevin Fabian Arsaputera et al. / Procedia Structural Integrity 72 (2025) 409–417

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strain, strain rate, and temperature must be considered; thus, the Johnson-Cook (JC) material model is employed. The material selected for this study is Aluminum 1100-H12, commonly used in various components. The plate undergoes significant plastic deformation, strain hardening, and thermal softening upon impact. The Johnson-Cook model describes the material’s response to strain rate, while deformation in the projectile is neglected, assuming it behaves as a rigid body. The equivalent stress ( ̅ ) is described by the following equation: ̅ = [ + ( ̅ ) ] [1 + ( ̅̇ ̅̇ 0 )][1 − ^ ] (4) Here, A, B, n, C, and m are material parameters obtained from experimental tests. ̅̇ ₀ is the reference strain rate, ̅ is the equivalent plastic strain, ̅̇ is the equivalent plastic strain rate, and ̂ is a temperature-related dimensionless parameter, defined as: ̂ = ( ( − − ) ) for < < (5) where is the instantaneous temperature, is the transition temperature, and is the melting temperature. The Johnson-Cook fracture model further requires consi deration of strain rate, stress triaxiality, and temperature’s influence on the equivalent failure strain, expressed as: ̅ = [ 1 + 2 ( 3 ( ̅ ))] [1 + 4 ( ̅̇ ̇ 0 )] [1 + ₅ ] (6) where ₁ through ₅ are material parameters derived from mechanical tests, with ₁, ₂, and ₃ representing stress triaxiality parameters, ₄ the strain rate -dependent damage parameter, and ₅ the temperature-dependent fracture strain parameter, the ratio / ̅ is the stress triaxiality, where is the mean stress, and ̅ is the equivalent stress. Table 1. Material properties of Aluminum 1100-H12. Properties Unit Value Modulus of elasticity, E N/mm2 65.762 × 103 Poisson’s ratio, v - 0.3 Density, ρ kg/m3 2700 Yield stress, A N/mm2 148.361 Strain hardening coefficient, B N/mm2 345.513 Strain hardening exponent, n - 0.183 Strain sensitivity coefficient, C - 0.001 Reference strain rate - 1 Thermal softening constant, m - 0.859 Melting temperature, Tmelt K 893 Transition temperature, T0 K 293 Specific heat, Cp J/kgK 920 Inelastic heat fraction, ɳ - 0.9 JC damage material constant D1 - 0.071 JC damage material constant D2 - 1.248 JC damage material constant D3 - − 1.142 JC damage material constant D4 - 0.147 JC damage material constant D5 - 0.0